Clamping device having barbed pin

ABSTRACT

Methods and apparatus are provided in which a clamping device for holding a work-piece comprises at least two clamping arms and at least one of the arms has a pin including a conical or pointed tip that at least partially penetrates a surface of the work-piece while in a clamped configuration.

FIELD OF THE INVENTION

[0001] The field of the invention is clamping devices and methods.

BACKGROUND OF THE INVENTION

[0002] The process of electroplating typically involves immersing a work piece into tanks having an electrolytic solution. Early systems describe work pieces being placed on racks that typically hang from an electric current carrying bus bar positioned above the tanks. The bus bar conducts a source of electrical current to the racks and through the work pieces to a ground terminal. To facilitate the plating process, there must be reliable electrical contact between the bus bar and the rack arm. It is known to use clamps to create the contact between the bus bar and the rack arm. Since the clamps may at least partially be emerged in the tanks, the clamps may be subject to corrosion caused by the electrolytic solution. Additionally, the clamps may become partially plated during the electroplating process.

[0003] U.S. Pat. No. 2,190,440 to Beebe (February 1940) teaches a clamp having an electrically conductive jaw that is covered by an insulating layer. While the insulating layer may provide some protection from the effects of the electrolytic solution, Beebe teaches that four clamps must be used to hold a panel, and therefore placement and removal of panels was time consuming. A simplified design of clamp known as the woodworker's steel spring clamp came into use and may have alleviated at least some of the problems associated with the time to place and remove panels. However, during the electroplating process the steel spring was being heated to such high temperatures that the spring would lose its tension and become less effective at holding a work piece.

[0004] U.S. Pat. No. 4,844,779 to Callahan (July 1989) and U.S. Pat. No. 5,456,814 to Metzka (October 1995) addressed the problem with the spring. The '779 patent teaches a clamp in which the spring is electrically insulated from the clamp, and therefore no detrimental heat build up occurs in the spring while the '814 patent teaches a spring-less device for holding a panel between a flat ended pin and another flat member. The '814 patent goes on to teach that pins may have an “electrically insulated coating”, but such coatings were difficult to replace since the process used to coat the pins also adhered the coatings to the pins.

[0005] U.S. Pat. No. 5,904,820 to Brown et al. (May 1999) teaches a clamp having two springs and clamp arms that are covered by a corrosion-resistant, fluid-tight and electrically insulating protective sleeve. The '820 patent also discloses terminal studs that contact the circuit board when the clamp is in a closed position. The terminal studs have “stud annular sheaths preferably made from the same electrically insulating material as arm sleeves.” A persisting problem with the clamp of the '820 patent, however, is that the tension is not sufficient to hold relatively heavy work pieces, and the protective coverings were susceptible to slipping off of the pin.

[0006] Thus, there is a need for improved clamps and methods of clamping in which the clamps have increased holding capability and the protective materials are more easily replaced yet not susceptible to slippage.

SUMMARY OF THE INVENTION

[0007] Methods and apparatus are provided in which a clamping device for holding a work-piece comprises at least two clamping arms and at least one of the arms has a pin including a conical or pointed tip that at least partially penetrates a surface of the work-piece while in a clamped configuration.

[0008] The present invention is also directed toward a method of clamping a work-piece to be plated including the steps of fitting a protective sleeve over a body portion of a first gripping pin, providing a second gripping pin, biasing the first and second gripping pins toward the work-piece such that at least one of the gripping pins penetrates a surface of the work-piece, and maintaining contact among the at least two gripping pins and the work-piece while the work-piece is being plated.

[0009] Another aspect of the present subject matter includes having at least one barb on a pin. The barb(s) operate to inhibit movement of a protective sleeve.

[0010] Various objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention, along with the accompanying drawings in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a side view of a clamp embodying the invention;

[0012]FIG. 2 is a side view of a set of pins embodying the invention;

[0013]FIG. 3a is a side view of a long shaft barb pin;

[0014]FIG. 3b is a side view of a short shaft barb pin;

[0015]FIG. 4 is a block diagram of a method embodying the invention.

DETAILED DESCRIPTION

[0016] Referring first to FIG. 1, a clamp 100 generally comprises a flight bar 110, a first arm 120, a second arm 130, a spring 140, a first gripping portion 150, a second gripping portion 160, a first pin 170, and a second pin 180.

[0017] A flight bar 110 is preferably made of copper and may operates as a negatively charged cathode bar. During a typical electroplating operation current is transmitted from the anode element through acid in a tank, the article to be plated and to the cathode bar.

[0018] The first arm 120 and second arm 130 are generally made of electrically conducting material (e.g. stainless steel). The arms are generally moveable between a clamped configuration and a released configuration. In a clamped configuration at least two gripping pins (not shown) contact a work-piece 190. In a released configuration less than two gripping pins contact a work-piece 190. The arms may be comprised of gripping portions 150 and 160 that are typically coated by a protective material. Such protective material is preferably resistant to the corrosive effects of an electroplating process. For example, plastisol may be used as a protective material. Plastisol is generally a mixture of vinyl resins and compatible plasticizers. Although polyvinyl chloride (PVC) is the dominant member, the family of vinyls comprises a number of resins based on the vinyl radical, (CH₂═CH—), or vinylidene radical, (CH2=C>).

[0019] Movement of the arms is generally biased by a spring 140 typically comprised of metal, but may also be comprised of any other material that provides tension and biases the arms toward each other and toward a work-piece 190 that is placed between the arms and between the pins 170 and 180. Bias of arms and gripping pins toward each other is preferred to be approximately 50 foot pounds per square inch (f.f.p.), however the pressure need only be sufficient to penetrate a work piece having a surface tension of 100 dynes/cm. Such penetration is preferred to be at least 15 millimeters in depth although a more shallow penetration may also be sufficient, and obvious variants will apply.

[0020] With respect to the first pin 170 and the second pin 180, the pins are generally covered by a protective material which may be neoprene, rubber, or any other suitable material that protects the pins from corrosion and buildup of metal plating. Because protective material is subject to wear, the material should be readily susceptible to replacement.

[0021] In FIG. 2, a set of pins generally comprises a first pin body 230 coupled to a first gripping portion 210 and a second pin body 240 coupled to a second gripping portion 220. While coupling of a pin body is generally accomplished by threading the pin body into a gripping portion, it should be appreciated that other suitable manners of coupling may be utilized. A first pin body 230 may be substantially encased by a protective material 250 (e.g. neoprene).

[0022] A first contact surface 235 of the first pin body 230 is shown as a flat surface, but other surface topographies are contemplated, especially conical. Since a contact surface aids in the electroplating process, it is generally required that the end be free from any protective material and constructed of electrically conductive material (e.g. 3/16 stainless steel).

[0023] With respect to a second pin body 240 and a second contact surface 245, the second contact surface is shown as a conical shape which comes to a point (substantially) on the end that contacts a work piece. While FIG. 2 depicts only one contact surface having a conical shape, in other embodiments there may be more than one conical contact surface. In any case, a conical contact surface aids in the gripping and holding capability of a clamp because the pointed end of the contact surface typically penetrates a surface of a work piece. Such penetration adds to the holding capability of a clamp. In a preferred embodiment, penetration into the surface of a work piece is at least 0.015 millimeters.

[0024]FIG. 3a exemplifies a long shaft pin having a pin body 310 and four barbs 320. The long shaft pin also has a threaded end 330 for use in coupling the pin to a clamp and a conical end 340 for use in holding a work piece. The barbs 320 operate to generally inhibit movement of a protective material (not shown) in the direction of the conical end 340. It should be recognized that a barb may operate to inhibit movement of a protective material in other directions as well.

[0025] A barb also referred to as a gripping pin barb is defined herein as an extension of a pin body that operates to inhibit movement of a sleeve or other protective material placed over the pin body. A barb preferably extends out from a pin body by at least 0.062 millimeters.

[0026]FIG. 3b exemplifies a short shaft pin having a pin body 350, two barbs 360, a threaded end 370, and a conical end 380. Of course additional configuration of a pin may be appropriate including those that have fewer or more barbs and those having a different shaped end from the conical end depicted.

[0027] In FIG. 4 a method of clamping a work piece to be plated includes the steps of 10 fitting a protective sleeve over a body portion of a first gripping pin, 20 providing a second gripping pin, 30 biasing the first and second gripping pins toward the work piece such that at least one of the gripping pins penetrates a surface of the work piece, 40 maintaining contact among the at least two gripping pins and the work piece while the work piece is being plated, and 50 inhibiting movement of the protective sleeve using gripping pin barbs.

[0028] Fitting a protective sleeve over a body portion of a first gripping pin 10 generally involves placing a sleeve over a body portion. If the body portion has barbs, this task may be hindered by the barbs, however, in preferred embodiments barbs are shaped and positioned to facilitate relatively easy placement of a protective sleeve over a body portion.

[0029] Methods of clamping a work piece to be plated generally utilize at least two opposing gripping pins that are biased toward each other and toward a work piece. A gripping pin may have a portion that is conical (i.e. substantially pointed) in shape and such conical portion may penetrate a surface of a work piece. Penetration of a work piece is achieved at least partially by biasing opposing pins against the work piece at a pressure sufficient to penetrate the work piece.

[0030] Thus, specific embodiments and applications of clamping devices and methods have been disclosed. It should be apparent, however, to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. 

What is claimed is:
 1. A device for holding a work-piece to be plated, comprising a plurality of clamping arms each having a gripping pin, wherein at least one gripping pin has a substantially conical tip that at least partially penetrates a surface of the work-piece when the clamping arms are in a clamped configuration.
 2. The device of claim 1, wherein the gripping pins are biased toward each other at a pressure of 50 foot pounds per square inch.
 3. The device of claim 1, wherein the gripping pins are biased toward each other at a pressure sufficient to penetrate said work-piece having a surface tension of at least 100 dynes/cm.
 4. The device of claim 3, wherein said penetration of the work piece is at least 0.015 millimeters +/−0.005 in depth.
 5. The device of claim 1, wherein the clamping arms are movable between the clamped configuration, in which at least two gripping pins contact the work-piece, and a released configuration, in which less than two gripping pins contact the work-piece.
 6. The device of claim 1, further comprising a protective material sized and positioned to substantially protect the gripping pin from being plated.
 7. The device of claim 6, wherein the gripping pin further comprises a body portion having a surface area and the protective material contacts substantially all of the surface area of the body portion.
 8. The device of claim 7, wherein the body portion comprises a barb that inhibits movement of the protective material in at least one direction.
 9. The device of claim 8, wherein the protective material is neoprene.
 10. The device of claim 1, wherein the work-piece comprises a panel and the device is coupled to a flight bar.
 11. The device of claim 1, wherein the conical tip tapers to a point and the point penetrates the surface of the work-piece up to 0.015 millimeters in depth.
 12. The device of claim 1, further comprising a spring that biases the clamping arms toward each other.
 13. A method of clamping a work-piece to be plated, comprising: biasing first and second gripping pins toward the work-piece such that at least one of the gripping pins penetrates a surface of the work-piece; and maintaining contact among the at least two gripping pins and the work-piece while the work-piece is being plated.
 14. The method of claim 13, wherein at least one of the gripping pins has a conical tip that facilitates penetration of the surface of the work-piece.
 15. The method of claim 14, further comprising fitting a protective sleeve over a body portion of a least one gripping pin.
 16. The method of claim 15, wherein the protective sleeve comprises neoprene.
 17. The method of claim 13, wherein the biasing step is accomplished at least partially by using a spring.
 18. The method of claim 13, further comprising the step of fitting a second protective sleeve over a body portion of the second gripping pin.
 19. The method of claim 18, further comprising the step of inhibiting movement of the protective sleeve using gripping pin barbs. 